When I attempt to go to that sub-domain, it is pulling up for me. It could possibly be that you haven't received the DNS update for this sub-domain yet due to DNS taking up to 24 hours to fully propagate in some instances.

You can modify your hosts file on your local computer to force the site to resolve right away. The entry you'd end up with would look like this:

192.249.112.231 test.welshgames.co.uk

Aside from that, you could simply wait longer until you get the most updated public DNS records for your domain, which are resolving that sub-domain currently if you don't have the records cached.